Three foreign oil workers, two Americans and a Briton, were freed on Monday by Nigerian militants who had held them hostage for five weeks, officials said.
The release of the three, employees of US oil services company Willbros, raised hopes for an end to three months of sabotage and kidnapping in the world's eighth largest oil exporting country that has cut shipments by a quarter.
The three men were handed to the governor of Nigeria's southern Delta state by an ethnic Ijaw leader, who had been negotiating with the militants on behalf of the government.
US and British diplomatic staff took the men for medical checks.
"(The three) are in very good health and high spirits," said Abel Oshevire, a spokesman for Delta state. "Of course, they are a bit agitated after a month in captivity."
The rebel Movement for the Emancipation of the Niger Delta (MEND) had demanded a greater share of the region's huge oil wealth, the release of two jailed Ijaw leaders and compensation for oil pollution as conditions for freeing the hostages.
It was not immediately clear what produced the breakthrough, but President Olusegun Obasanjo is due to fly to Washington on Tuesday and pressure had been building up for an end to the standoff over the hostages.